Plasma density control on substrate edge

ABSTRACT

Embodiments of the present disclosure generally relate to apparatuses for reducing particle contamination on substrates in a plasma processing chamber. In one or more embodiments, an edge ring is provided and includes a top surface, a bottom surface opposite the top surface and extending radially outward, an outer vertical wall extending between and connected to the top surface and the bottom surface, an inner vertical wall opposite the outer vertical wall, an inner lip extending radially inward from the inner vertical wall, and an inner step disposed between and connected to the inner wall and the bottom surface. During processing, the edge ring shifts the high plasma density zone away from the edge area of the substrate to avoid depositing particles on the substrate when the plasma is de-energized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/947,393, filed Apr. 6, 2018, which claims benefit of U.S. Appl. No.62/482,915, filed Apr. 7, 2017, which are herein incorporated byreference.

BACKGROUND Field

Implementations of the present disclosure generally relate to anapparatus for reducing particle contamination on substrates in a plasmaprocessing chamber.

Description of the Related Art

Plasma-enhanced chemical vapor deposition (PECVD) process is a chemicalprocess where electro-magnetic energy is applied to at least oneprecursor gas or vapor to transform the precursor into a reactiveplasma. There are many advantages in using PECVD, including but notlimited to lowering the temperature required to form a film, increasingthe rate of formation of the film, enhancing the properties of thelayers being formed. Particles of the gas or vapor ionized by the plasmadiffuse through the plasma sheath and are absorbed onto the substrate toform a thin film layer. Plasma may be generated inside the processingchamber, i.e., in-situ, or in a remote plasma generator that is remotelypositioned from the processing chamber. This process is widely used todeposit materials on substrates to produce high-quality andhigh-performance semiconductor devices.

Particle contamination during plasma processes such as PECVD is a majorimpediment to the deposition and etching of thin films during theproduction of these semiconductor devices. Therefore, improved apparatusare needed for reducing particle contamination in a plasma processingchamber.

SUMMARY

Implementations of the present disclosure generally relate to anapparatus for reducing particle contamination on substrates in a plasmaprocessing chamber. In one implementation, the apparatus for reducedparticle contamination includes a chamber body, and a lid coupled to thechamber body. The chamber body and the lid define a processing volumetherebetween. The apparatus also includes a substrate support disposedin the processing volume and an edge ring. The edge ring includes aninner lip disposed over a substrate, a top surface connected to theinner lip, a bottom surface opposite the top surface and extendingradially outward from the substrate support, and an inner step betweenthe bottom surface and the inner lip.

In another implementation, a plasma processing apparatus is disclosedand includes a chamber body and a lid coupled to the chamber body. Thechamber body and the lid define a processing volume therebetween. Theplasma processing apparatus further includes a substrate supportdisposed in the processing volume and an edge ring disposed on thesubstrate support. The edge ring includes an inner lip extendingradially inward and a top surface connected to the inner lip. The topsurface of the edge ring is inclined. The edge ring also includes abottom surface opposite the top surface and extending radially outwardfrom the substrate support and an inner step between the bottom surfaceand the inner lip disposed on the substrate support.

In yet another implementation, a plasma processing apparatus isdisclosed and includes a chamber body and a lid coupled to the chamberbody. The chamber body and the lid define a processing volumetherebetween. The plasma processing apparatus also includes a substratesupport disposed in the processing volume and an edge ring disposed onthe substrate support. The edge ring includes an inner lip extendingradially inward and a top surface connected to the inner lip. The topsurface of the edge ring is chamfered. The edge ring also includes abottom surface opposite the top surface and extending radially outwardfrom the substrate support and an inner step between the bottom surfaceand the inner lip disposed on the substrate support.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toimplementations, some of which are illustrated in the appended drawings.It is to be noted, however, that the appended drawings illustrate onlyexemplary implementations and are therefore not to be consideredlimiting of scope, as the disclosure may admit to other equallyeffective implementations.

FIG. 1 shows a schematic cross-sectional view of a plasma processingchamber according to one implementation described herein.

FIG. 2 shows a partial cross-sectional view of an edge ring according toone implementation described herein.

FIG. 3 shows a partial cross-sectional view of an edge ring according toanother implementation described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. The figures are not drawn to scale and may be simplifiedfor clarity. It is contemplated that elements and features of oneimplementation may be beneficially incorporated in other implementationswithout further recitation.

DETAILED DESCRIPTION

FIG. 1 shows a schematic cross-sectional view of a plasma processingchamber 100 according to one implementation described herein. Theprocessing chamber 100 may be a plasma enhanced chemical vapordeposition (PECVD) chamber or other plasma enhanced processing chamber.An exemplary processing chamber which may benefit from theimplementations described herein is the PRODUCER® series of PECVDenabled chambers, available from Applied Materials, Inc., Santa Clara,Calif. It is contemplated that other similarly equipped processingchambers from other manufacturers may also benefit from theimplementations described herein. The processing chamber 100 features achamber body 102, a substrate support 104 disposed inside the chamberbody 102, and a lid assembly 106 coupled to the chamber body 102 andenclosing the substrate support 104 in an internal processing volume120. Substrates 154 are provided to the processing volume 120 through anopening 126.

An electrode 108 may be disposed adjacent to the chamber body 102 andseparating the chamber body 102 from other components of the lidassembly 106. The electrode 108 may be part of the lid assembly 106, ormay be a separate side wall electrode. The electrode 108 may be anannular, or ring-like member, and may be a ring electrode. The electrode108 may be a continuous loop around a circumference of the processingchamber 100 surrounding the processing volume 120, or may bediscontinuous at selected locations if desired. The electrode 108 mayalso be a perforated electrode, such as a perforated ring or a meshelectrode. The electrode 108 may also be a plate electrode, for example,a secondary gas distributor.

An isolator 110 contacts the electrode 108 and separates the electrode108 electrically and thermally from a gas distributor 112 and from thechamber body 102. The isolator 110 may be made from or contain one ormore dielectric materials. Exemplary dielectric materials can be orinclude one or more ceramics, metal oxides, metal nitrides, metaloxynitrides, silicon oxides, silicates, or any combination thereof. Forexample, the isolator 110 may contain or be formed from aluminum oxide,aluminum nitride, aluminum oxynitride, or any combination thereof. Thegas distributor 112 features openings 118 for admitting process gas intothe processing volume 120. The process gases may be supplied to theprocessing chamber 100 via a conduit 114, and the process gases mayenter a gas mixing region 116 prior to flowing through the openings 118.The gas distributor 112 may be coupled to a source of electric power142, such as an RF generator. DC power, pulsed DC power, and pulsed RFpower may also be used.

The electrode 108 may be coupled to a tuning circuit 128 that controls aground pathway of the processing chamber 100. The tuning circuit 128comprises an electronic sensor 130 and an electronic controller 134,which may be a variable capacitor. The tuning circuit 128 may be an LLCcircuit comprising one or more inductors 132. The tuning circuit 128features a first inductor 132A in series with the electronic controller134 and a second inductor 132B in parallel with the electroniccontroller 134. The electronic sensor 130 may be a voltage or currentsensor, and may be coupled to the electronic controller 134 to afford adegree of closed-loop control of plasma conditions inside the processingvolume 120.

A second electrode 122 may be coupled to the substrate support 104. Thesecond electrode 122 may be embedded within the substrate support 104 orcoupled to a surface of the substrate support 104. The second electrode122 may be a plate, a perforated plate, a mesh, a wire screen, or anyother distributed arrangement. The second electrode 122 may be a tuningelectrode, and may be coupled to a second tuning circuit 136 by aconduit 146, for example a cable having a selected resistance, such asabout 50Ω, disposed in a shaft 144 of the substrate support 104. Thesecond tuning circuit 136 may have a second electronic sensor 138 and asecond electronic controller 140, which may be a second variablecapacitor. The second electronic sensor 138 may be a voltage or currentsensor, and may be coupled to the second electronic controller 140 toprovide further control over plasma conditions in the processing volume120.

A third electrode 124, which may be a bias electrode and/or anelectrostatic chucking electrode, may be coupled to the substratesupport 104. The third electrode 124 may be coupled to a second sourceof electric power 150 through a filter 148 contained in an electriccircuit 180. The filter 148 may be an impedance matching circuit. Thesecond source of electric power 150 may be DC power, pulsed DC power, RFpower, pulsed RF power, or any combination thereof.

The lid assembly 106 and substrate support 104 of FIG. 1 may be usedwith any processing chamber for plasma or thermal processing. Chambersfrom other manufacturers may also be used with the components describedabove.

The substrate support 104 may contain or be formed from one or moremetallic or ceramic materials. Exemplary metallic or ceramic materialscan be or include one or more metals, metal oxides, metal nitrides,metal oxynitrides, or any combination thereof. For example, thesubstrate support 104 may contain or be formed from aluminum, aluminumoxide, aluminum nitride, aluminum oxynitride, or any combinationthereof. In one implementation, the surface of the substrate support 104may be configured to support an edge ring 160 during processing.

In another implementation, the inner diameter of the edge ring 160 maybe greater than the outer diameter of the substrate 154. In such animplementation, one, two, three, four, or more holders 156 (one holderis depicted in the view of FIG. 1) may be configured to support the edgering 160 when transferring the substrate 154 to and from the substratesupport 104. Multiple holders 156 may be located on the inner wall ofthe chamber body 102 at locations spaced away from each other. In one ormore embodiments, the substrate support 104 is lowered to align with theopening 126. As the substrate support 104 is being lowered towards theopening 106, the edge ring 160 makes contact to and is supported by theholders 156. Once the substrate support 104 is aligned with the opening126, the substrate 154 can be transferred to or from the substratesupport 104 via the opening 126 when introducing or removing thesubstrate 154 into the processing chamber 100. As the substrate support104 is being raised away from the opening 126, the substrate support 104makes contact to and supports the edge ring 160 which is lifted from theholders 156. Once in position for processing, the substrate support 104maintains support of the edge ring 160.

The edge ring 160 may be formed from one or more ceramic materials andmay have an annular shape. In one or more examples, each of thesubstrate support 104 and the edge ring 160 independently includes oneor more ceramic materials. The edge ring 160 may be configured to engagethe substrate support 104, in some cases resting directly on thesubstrate support 104. In one implementation, the substrate support 104may have an annular ledge formed along the circumference of thesubstrate supporting surface. The annular ledge may be configured tocouple to and support the edge ring 160, for example with the edge ring160 resting on the annular ledge, when the substrate support 104 is inthe processing position.

The edge ring 160 may be sized to extend radially outward from thesubstrate support 104. As such, an outer diameter of the edge ring 160may be greater than an outer diameter of the substrate support 104.Thus, a portion of the bottom surface of the edge ring 160 which extendsradially beyond the substrate support 104 may be configured to engagethe holder 156. The holder 156 may be a continuous or discontinuousannular shelf extending from a chamber side wall or liner radiallyinward towards the substrate support. In one implementation, the holder156 may be three protrusions distributed, equally or unequally, aroundthe processing chamber 100 at a peripheral portion thereof. In anotherimplementation, the protrusions may be more than three protrusions,which may be distributed equally, unequally, and/or symmetrically aroundthe processing chamber 100 periphery. The holder 156 may have a supportsurface that is substantially parallel to a contact surface of the edgering 160. Alternately, the holder 156 may have a support surface that isnot parallel to the contact surface of the edge ring. For example, insome cases, the holder 156 may have a downward sloping support surfaceto reduce areal contact between the holder 156 and the edge ring 160. Inoperation, the holder 156 engages the edge ring 160 to hold the edgering 160 away from the substrate 154 while the substrate 154 is removedfrom the processing chamber 100.

The edge ring 160 may contain or be formed from one or more ceramicmaterials. In one implementation, the edge ring 160 is formed from orcontains aluminum nitride. The edge ring 160 may include an inner lipthat extends over and above the substrate 154. In one implementation,the inner lip may have a curved or rounded edge. In anotherimplementation, the inner lip may have a flat vertical inner wall.

In one implementation, the edge ring 160 is an annular ring with a flattop surface. In the implementation of FIG. 2, the edge ring 260 is anannular ring with an inclined top surface 262. FIG. 2 shows a partialcross-sectional view of an edge ring according to one implementationdescribed herein. The edge ring 260 can be utilized in the processingchamber 100. The edge ring 260 is an annular ring with an inclined topsurface 262 that is higher towards the inner circumference and lowertowards the outer circumference. The inclined top surface 262 may be abeveled surface. In other words, the inclined top surface 262 decreasesradially outward. The edge ring 260 includes an inner lip 264. Theinclined top surface 262 is in connection with and part of the inner lip264. The inner lip 264 extends radially outward towards the innercircumference of the edge ring 260. The inner lip 264 may have a flat,vertical inner wall. The inner lip 264 extends over and above thesubstrate 154. The inner lip 264 is in connection with an inner step266. The inner step 266 is a right angled protrusion. The inner step 266is located below the inner lip 264 and radially in from the inner lip264. The inner step 266 has a bottom surface that engages the substratesupport 104. The inner step 266 is in connection with a bottom surface268 and the inner lip 264. The bottom surface 268 is opposite theinclined top surface 262 and connected to the inclined top surface 262by a vertical wall 270. The bottom surface 268 extends radially outwardfrom the substrate support 104 and is configured to engage the holder156.

FIG. 3 shows a partial cross-sectional view of an edge ring according toanother implementation described herein. In the implementation of FIG.3, the edge ring 360 is an annular ring with an inclined top surface362. The edge ring 360 can be utilized in the processing chamber 100.The edge ring 360 is similar to the edge ring 260 including an inner lip364, an inner step 366, a bottom surface 368, and a vertical wall 370.The edge ring 360 is an annular ring with an inclined top surface 362that is lower towards the inner circumference and higher towards theouter circumference. In other words, the inclined top surface 362increases in height radially outward. The inclined top surface 362 maybe a beveled surface. In one implementation the inclined top surface 362includes a chamfered edge 372. In another implementation, the inclinedtop surface 362 has rounded edges.

In operation, plasma is generated in the processing volume 120. Uponenergizing a plasma in the processing volume 120, a potential differenceis established between the plasma and the first electrode 108. Apotential difference is also established between the plasma and thesecond electrode 122. The plasma thus formed can produce particles inthe reactive zone of the plasma. The particles typically remainelectrostatically charged while the plasma is energized, so theparticles remain mostly trapped within the plasma sheath. To avoiddepositing the particles on the substrate being processed when theplasma is de-energized, the edge ring 160 shifts the high plasma densityzone away from the edge area of the substrate. The elevation of the edgering 160 from the substrate support 104 pushes the particles away fromthe substrate 154 towards an exhaust 152. Additionally, a potentialdifference may be established between the plasma and the edge ring 160repelling the charged particles away from the substrate 154.

The edge ring also provides for more control of the plasma density nearthe substrates edge reducing edge spray defects during plasmatermination. In certain implementations, the edge ring provides asurface to protect the substrate from falling particles but also todirect the particles away from the substrate. The plasma particles areinstead directed towards the exhaust and away from the substrate.

While the foregoing is directed to implementations of the presentdisclosure, other and further implementations of the disclosure may bedevised without departing from the basic scope thereof.

1. An edge ring, comprising: a top surface; a bottom surface oppositethe top surface and extending radially outward; an outer vertical wallextending between and connected to the top surface and the bottomsurface; an inner vertical wall opposite the outer vertical wall; aninner lip extending radially inward from the inner vertical wall; and aninner step disposed between and connected to the inner wall and thebottom surface, wherein the inner step has a first surface adjacent asecond surface.
 2. The edge ring of claim 1, wherein the inner lipextends at a right angle relative to the inner vertical wall.
 3. Theedge ring of claim 1, wherein the top surface of the edge ring isinclined.
 4. The edge ring of claim 1, wherein the top surface of theedge ring is inclined higher towards the inner circumference of the edgering and lower towards the outer circumference of the edge ring.
 5. Theedge ring of claim 1, wherein the top surface of the edge ring isinclined lower towards the inner circumference of the edge ring andhigher towards the outer circumference of the edge ring.
 6. The edgering of claim 1, wherein the top surface of the edge ring is flat. 7.The edge ring of claim 1, wherein the edge ring has rounded edges. 8.The edge ring of claim 1, wherein the top surface of the edge ring ischamfered.
 9. The edge ring of claim 1, wherein the edge ring comprisesa ceramic material.
 10. The edge ring of claim 1, wherein the edge ringcomprises aluminum.
 11. An edge ring, comprising: a top surface; abottom surface opposite the top surface and extending radially outward;an outer vertical wall extending between and connected to the topsurface and the bottom surface; an inner vertical wall opposite theouter vertical wall; an inner lip extending radially inward from theinner vertical wall, wherein the inner lip extends at a right anglerelative to the inner vertical wall; and an inner step disposed betweenand connected to the inner wall and the bottom surface.
 12. The edgering of claim 11, wherein the top surface of the edge ring is inclined.13. The edge ring of claim 11, wherein the top surface of the edge ringis inclined higher towards the inner circumference of the edge ring andlower towards the outer circumference of the edge ring.
 14. The edgering of claim 11, wherein the top surface of the edge ring is inclinedlower towards the inner circumference of the edge ring and highertowards the outer circumference of the edge ring.
 15. The edge ring ofclaim 11, wherein the top surface of the edge ring is flat.
 16. The edgering of claim 11, wherein the edge ring has rounded edges.
 17. The edgering of claim 11, wherein the top surface of the edge ring is chamfered.18. The edge ring of claim 11, wherein the edge ring comprises a ceramicmaterial.
 19. The edge ring of claim 11, wherein the edge ring comprisesaluminum.
 20. An edge ring, comprising: a top surface; a bottom surfaceopposite the top surface and extending radially outward; an outervertical wall extending between and connected to the top surface and thebottom surface; an inner vertical wall opposite the outer vertical wall;an inner lip extending radially inward from the inner vertical wall,wherein the inner lip extends at a right angle relative to the innervertical wall; and an inner step disposed between and connected to theinner wall and the bottom surface, wherein the inner step has a firstsurface adjacent a second surface, wherein the edge ring comprises aceramic material.